Computer-assisted video evaluation of surgical skills

Compact video cameras have allowed the review of operations in self-directed learning sessions. Controlling the video viewing process by computer allows the selection of specific videotape segments containing the desired psychomotor skills to be evaluated--in this study, the steps involving laparoscopic tubal banding. Six faculty members were able to evaluate 23 videotapes efficiently without knowledge of the resident operator's identity. Because the computer allowed selection of only those frames of the videotape containing the skills to be evaluated, the duration of videotape seen was reduced by an average of 34% from the actual surgical time, with an increase in time saved as experience with the system was gained. Faculty members evaluated these events using a self-made checklist. It was possible to calculate the performance scores of each resident for the individual psychomotor skill components of the reviewed procedure. Computer-assisted video evaluation of surgical skills is technically feasible, allowing time-efficient review by multiple evaluators. With the development of psychometrically valid checklists for use with this technology, computer-assisted video evaluation of surgical skills may provide a new, innovative means of assessing surgical skills and training.     

The strain-rate,temperature and pressure dependence of yield of isotropic poly(methylmethacrylate) and poly(ethylene terephthalate)

The yield behaviour of poly(methylmethacrylate) (PMMA) has been investigated in tension and compression over a range of testing temperatures and strain-rates. Both tensile and compressive yield stresses were found to increase monotonically with increasing strainrate and decreasing temperatures. Compressive yield stresses were in general found to be more dependent on strain-rate.The results of this investigation have been correlated with previous published data for the dependence of the torsional yield stress of PMMA on hydrostatic pressure. This was done by a modification of a theory proposed by Robertson which uses the internal viscosity approach to yield in glassy polymers. The modified theory clearly explains the temperature and strain-rate dependence of the yield stress and provides a quantitative explanation of the differences in behaviour between tension and compression in terms of the dependence of yield on the hydrostatic component of the applied stress.The tensile yield behaviour of isotropic amorphous poly(ethylene terephthalate) (PET) sheets has also been investigated over a wide range of temperatures and strain-rates. No torsion or compressive yield stresses are available because of the sheet form of the PET, but the results obtained in tension are shown to be fully consistent with the above theory, and with other published work.Paper presented at Cambridge, April 1970, during conference on Yield, Deformation and Fracture of Polymers.     

Observations on the A2 England influenza epidemic: a clinicopathological study

A clinicopathological study of the 1972-1973 A2 England influenza epidemic is presented. In fatal cases early necrosis of myofibrils was present in those patients who died within 24 hours of the onset of the influenza symptoms. At 5 days gross changes were present. These were largely resolved by the eighteenth day of illness. In 42 patients treated at home, transient ECG changes were found in 18 cases. These included ST-segment deviation, T-wave inversion, flattening of the T wave, sinus bradycardia, sinus tachycardia, nodal rhythm, and atrial fibrillation. Permanent changes were observed in one patient and in an additional patient admitted to hospital with permanent A-V block.